An Updated Analysis on the Diet of Lemon Sharks (Negaprion brevirostris)

Although many studies on the diet of juvenile lemon sharks (Negaprion brevirostris) have been published, publications on the diet of sub-adult and adult lemon sharks are lacking. An analysis of the diet of lemon sharks collected from 2011 - 2018 in the South Atlantic and Gulf of Mexico was conducted on 67 lemon sharks, ranging from 179 to 270 cm in fork length (L). Of the 67 stomachs, 53 (79.1%) had prey items present. To quantify the diet of lemon sharks, the Index of Relative Importance (IRI) (a common method) was chosen which quantifies diet numerically (N), gravimetrically (W), and considers the frequency of occurrence (O). The use of these three variables eliminates biases that less comprehensive indices may fail to account for. The Index of Relative Importance was further expressed as a percentage value to allow for comparison among studies. Based on %IRI, lemon sharks are mainly piscivorous (60.2%), primarily Lutjanus campechanus and Caranx hippos but also predate heavily on both molluscs (35.8%) and other elasmobranch species (4.21%). Other prominent prey items include octopodidae sp. (35.4%). These findings indicate a clear ontogenetic shift in lemon shark diet, as molluscs, specifically octopodidae sp., become more important in the diet of adults and sub-adults than in the diet of juveniles. Overall, the diet of adult and sub-adult lemon sharks is more evenly distributed across fish, molluscs and elasmobranchs whereas the diet of juveniles contains higher proportions of fish and crustaceans when compared with other prey, especially molluscs.

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Primary Presenter: Owen Fleischer, University of Rhode Island (fleischerowen1@uri.edu)

Authors:

John Carlson, NOAA  (john.carlson@noaa.gov)

Annsli Hilton, NOAA  (annsli.f.hilton@noaa.gov)

Alyssa Mathers, NOAA  (alyssa.mathers@noaa.gov)